SUNKLANDS OF PORT PHILLIP BAY AND BASS STRAIT 109 
Flinders Island, in Victoria, and in Tasmania (the Great Lake 
and at Waratah) ; it also occurs as a fossil in the freshwater lime- 
stone underlying the Lower Pleistocene consohdated dunes at 
Burrabong Creek near Cape Schanck, Victoria. HydrieTla 
australis (Lam.) is found in Tasmania only in the rivers flowing 
northwards into Bass Strait. 
Although the earthworms are not found as fossils, Michaelson 
considers some of the Oligochaeta are most important for the 
purposes of palaeogeography. Stephenson (1930) maintains that 
they are of comparatively recent origin, and points out that, as 
their food consists of leaves and vegetable mould, they could have 
only originated after the spread of dicotyledonous plants which, 
too, took place in the Cretaceous. The recent origin of many 
present day genera, he observes, is indicated by the extraordinary 
variability of their species: the differentiation of the several 
families, and the evolution of the numerous genera, have occurred 
in the Tertiary and Quaternary. He cites the subfamily Megasco- 
leeinae, in a number of which the perichaetine arrangement of the 
setae is a fairly recent acquirement. This subfamily is typical of 
Australia and India, but is found to a lesser extent in the Malay 
Peninsula and Archipelago, the Philippines, China, Japan, Poly- 
nesia, and North America. The following is, as far as known, a 
tabular comparison of its Australia distribution : 
Genera Tasmania. Victoria. N.S.W. Queensland. 
Plutellus .... — — — 
Megascolides . . — — — 
Spenceriella . . — 
Notoscolex . . — — — — 
Megascolex . . — — — — 
Diporochaeta . . — — 
Perionyx .... — — 
Digaster .... — — 
Perissogaster . . — — 
Pidymogaster . . — 
Pheretima . . — 
Diplotrema . . — 
Spencer (1900) states that Megascolides and Diporochaeta are 
distinctly characteristic of Victoria (and Tasmania), the first- 
named spreading to a slight extent up the east coast of Australia 
(Spencer, 1892). The two genera are striking evidence of a 
former land connection between Victoria and Tasmania. 
Stephenson (1930) points out that earthworms must depend 
